using System.Collections.Generic;

namespace PKHeX.Core
{
    /// <summary>
    /// Encounter Slot found in <see cref="GameVersion.Gen2"/>.
    /// </summary>
    /// <remarks>
    /// Referenced Area object contains Time data which is used for <see cref="GameVersion.C"/> origin data.
    /// </remarks>
    /// <inheritdoc cref="EncounterSlot"/>
    public sealed record EncounterSlot2 : EncounterSlot, INumberedSlot
    {
        public override int Generation => 2;
        public byte SlotNumber { get; }
        public override Ball FixedBall => Ball.Poke;

        public EncounterSlot2(EncounterArea2 area, byte species, byte min, byte max, byte slot) : base(area, species, species == 201 ? FormRandom : 0, min, max)
        {
            SlotNumber = slot;
        }

        protected override void ApplyDetails(ITrainerInfo sav, EncounterCriteria criteria, PKM pk)
        {
            base.ApplyDetails(sav, criteria, pk);

            var pk2 = (PK2)pk;

            if (GetSlotType() == SlotType.Headbutt)
            {
                while (!IsTreeAvailable(pk2.TID))
                    pk2.TID = Util.Rand.Next(ushort.MaxValue + 1);
            }

            if (Version == GameVersion.C)
                pk2.Met_TimeOfDay = ((EncounterArea2)Area).Time.RandomValidTime();
        }

        private static readonly Dictionary<int, int> Trees = new()
        {
            { 02, 0x3FF_3FF }, // Route 29
            { 04, 0x0FF_3FF }, // Route 30
            { 05, 0x3FE_3FF }, // Route 31
            { 08, 0x3EE_3FF }, // Route 32
            { 11, 0x240_3FF }, // Route 33
            { 12, 0x37F_3FF }, // Azalea Town
            { 14, 0x3FF_3FF }, // Ilex Forest
            { 15, 0x001_3FE }, // Route 34
            { 18, 0x261_3FF }, // Route 35
            { 20, 0x3FF_3FF }, // Route 36
            { 21, 0x2B9_3FF }, // Route 37
            { 25, 0x3FF_3FF }, // Route 38
            { 26, 0x184_3FF }, // Route 39
            { 34, 0x3FF_3FF }, // Route 42
            { 37, 0x3FF_3FF }, // Route 43
            { 38, 0x3FF_3FF }, // Lake of Rage
            { 39, 0x2FF_3FF }, // Route 44
            { 91, 0x200_1FF }, // Route 26
            { 92, 0x2BB_3FF }, // Route 27
        };

        internal bool IsTreeAvailable(int trainerID)
        {
            if (!Trees.TryGetValue(Location, out var permissions))
                return false;

            var pivot = trainerID % 10;
            var type = Area.Type;
            return type switch
            {
                SlotType.Headbutt => (permissions & (1 << pivot)) != 0,
                /*special*/ _ => (permissions & (1 << (pivot + 12))) != 0,
            };
        }

        // we have "Special" bitflag. Strip it out.
        public SlotType GetSlotType() => Area.Type & (SlotType)0xF;
    }
}